Tissue cerebral

In other applications of CT, orally administered barium sulfate or a water-soluble iodinated CM is used to opacify the GI tract. Xenon, atomic number 54, exhibits similar x-ray absorption properties to those of iodine. It rapidly diffuses across the blood brain barrier after inhalation to saturate different tissues of brain as a function of its lipid solubility. In preliminary investigations (99), xenon gas inhalation prior to brain CT has provided useful information for evaluations of local cerebral blood flow and cerebral tissue abnormalities. Xenon exhibits an anesthetic effect at high concentrations but otherwise is free of physiological effects because of its nonreactive nature. 

Measurements of regional cerebral blood flow by PET and of cerebral perfusion by SPECT often detect functional abnormalities before CT or MRI identifies morphological abnormalities. The function of the cerebral tissue depends critically on the regional cerebral blood flow (rCBF) and rate of metabolism (see Ch. 31). Impairment of blood flow or the rate of consumption of 02 or glucose constitutes a pathological condition which can be... 

Griffin, J.L. and Corcoran, O., High-resolution magic-angle spinning 13C NMR spectroscopy of cerebral tissue, Magn. Reson. Mater. Phys. Biol. Med., 18,1352, 2005. 

Nicotine, 4 phenylpyridine, and hydrazine, administered to mice, prevented the decrease in dopamine metabolite levels induced by MPTP, but there was no significant effect on dopamine levels. The compounds did not inhibit monoamine oxidase (MAO) activity in cerebral tissue in vivo. In vitro, an extract produced significant inhibition of MAO A and B activities in the... 

The TET-induced inhibitory influence on cyclic 3 ,5 -AMP phosphodiesterase (PDE) activities precedes edema formation in the rat brain [74]. lb clarify the mechanism of the protective action of EGb against TET-toxidty in rats, in vitro and ex vivo effects of EGb on PDE activities of cerebral tissue were investigated [75]. Higher concentrations of EGb (5-250 mg/L) inhibited the PDE activity in the brain in normal rats, whereas lower concentrations (0.25-4.0 mg/L) of EGb enhanced the activity of the enzyme. The inhbitory effect of TET on the high affinity PDE activity (measured with 0.25 ftM cyclic AMP) of the brain was diminished in the presence of low EGb concentrations. Furthermore, preventive and curative treatment of 1 El-poisoned rats with EGb (100 mg/kg, p.o., for 7 days) prevented both the formation of edema and the fall of PDE activity induced by TET alone. These results suggested the antiedema action of EGb might be partly associated with its modulating influences on cellular cyclic AMP levels via activation of membrane-bound PDE. 

As shown in Figure (1), injected [uC]2-deoxy-D-glucose ([UC]DG) is transported toward cerebral tissue through the Mood brain barrier and then phosphorylated into [MC]DG-diphosphate ([l4C]DG-6P), which accumulates in the cells. Measuring radioactivity in brain sections by autoradiography, it is possible to calculate local cerebral glucose utilization (LCGU) [116]. 

Brunet, J. F. M., Berger, F., Amaltifano, G., and Benabid, A. L. 1994. Chemolabeling of frozen cerebral tissue proteins and immunopurified products with biotin and digoxigenin Physicochemical characteristics of biotinylated and digoxigeninated products. Anal. Biochem. 222 76-80. 

Gotow T, Miyaguchi K, Hashimoto PH (1991) Cytoplasmic architecture of the axon terminal filamentous strands specifically associated with synaptic vesicles. Neuroscience 40 587-98 Gower H, Rodnight R, Brammer MJ (1986) Ca2+ sensitivity of Ca2+-dependent protein kinase activities toward intrinsic proteins in synaptosomal membrane fragments from rat cerebral tissue. J Neurochem 46 440-7... 

EEG level fields are easily induced in tissues by weak radio and microwave fields at frequencies of 100-1000 MHz with incident energies around 1.0 mW/cm2, and electric gradients in air of 60-100 V/m. When sinusoidally modulated at ELF frequencies, particularly below 20 Hz, they alter cation binding in cerebral tissue. These are also "windowed" reactions, as discussed below, and relate to the low frequency modulation of the imposed field. 

Weak, ELF fields at frequencies from 1 to 75 Hz and 5 to 100 V/m in air were tested for their effects on t5Ca2+ efflux from freshly isolated chick and cat cerebral tissue (23). Tissue gradients were estimated to be in the range of 0.1 pV/cm. Field exposures resulted in a general trend toward a reduction in the release of preincubated 1 5Ca2+. Maximum decreases occurred at 6 and 16 Hz and were in the range from 12 to 15 percent. 

Threshold fields were around 10 and 56 V/m in air for chick and cat tissues, respectively, but sensitivity decreased at 100 V/m. Thus, calcium binding in chick and cat cerebral tissue exhibited frequency and amplitude windows in responses to these extremely weak fields (Figure 2B). 

This problem has been formulated theoretically by calculating the minimum electric field strength required to produce the alteration in Ca2" binding observed in chick cerebral tissue exposed to 147 and 450 MHz fields (22, 57), if the field interaction occurred by a thermal energy transfer mechanism (67). 

Bawin, S. M. Adey Sabbot, I. M. Ionic factors in release of t5Ca2 + from chick cerebral tissue by electromagnetic fields. Proc. Nat. Acad. Sci. USA 1978, 7J5, 6314-6318. 

Bawin, S. M. Lin-Liu, S. Adey, W. R. Influence of weak electromagnetically induced pulsating current on Ca binding in isolated cerebral tissue. American Electrochemical Society,... 

Dijkhuizen RM, Knollema S, van der Worp HB, Ter Horst GJ, De Wildt DJ, Berkelbach van der Sprenkel JW, Tulleken KA, Nicolay K (1998) Dynamics of cerebral tissue injury and perfusion after temporary hypoxia-ischemia in the rat evidence for region-specific sensitivity and delayed damage. Stroke 29 695-704... 

CT and MRI have been used extensively to show acute cerebral ischemia (stroke) and its sequelae. While CT is mainly used to exclude hemorrhage, it is very specific in detecting changes in the water content of ischemic cerebral tissues. 

Primary cultures of astrocytes are made from newborn rat cerebral cortex according to Dehouck et al. (1990). The meninges is cleaned off and the brain tissue is forced gently through a nylon sieve. DMEM supplemented with 10 % fetal calf serum, 2 mM glutamine, and 50 pg/ml of gentamicin is used for the dissociation of cerebral tissue and development of astrocytes. 

Q3 Post-mortem examinations of the brains of patients with Alzheimer s disease show loss of cortical neurones and abnormal depositions of proteins in the cerebral tissues. The normal structure of the brain is modified by /l-amyloid plaques, sometimes called senile plaques, and neurofibrillary tangles produced by abnormal neurones. Neurochemical changes in the brain occur, mainly involving cholinergic systems but also other neurotransmitters and neuro modulators. 

There is a loss of cortical neurones and abnormal deposition of proteins /l-amyloid and neurofibrillary tangles in the cerebral tissue. 

Cerebral tissues were homogenized with a glass homogenizer and used as the source of the diesterase activity. 

Perfusion MRI In contrast to diffusion MRI that examines the movement of fluid through tissues, perfusion MRI determines blood flow on the basis of measures of blood volume. Perfusion-weighted imaging (PWI) can determine cerebral tissue... 

Cerebral tissue acidosis following ischemia or flaumatic brain injury contributes to cytotoxic brain edema formation. In vitro lactacidosis induces swelling of glial cells by intracellular Na" - and Cl accumulation by the Na" /H+-antiporter, Cr/HCOs antiporters, and the Na -K -2C1 cotransport (Staub et al., 1990 Ringel et al., 2006a). 

Arterial spin-tagged perfusion MRI is performed by inverting the v ater protons in the blood of the arteries supplying blood to the tissue of interest. Typically, in brain, the carotid arteries are used as the supply. The original description of the method (Detre et al., 1992 Williams et al., 1992) uses a continuous narrow band RF inversion of the protons in the arterial blood, outside of the imaged slice, before and after excitation to cause a steady-state loss of signal in cerebral tissue. The signal loss is related to tissue perfusion (Detre et al., 1992) by ... 

Perfusion in cerebral tissue with normal vasculature is controlled by metaboHc demand, allowing use of regional quantitative perfusion measures to detect neurodegeneration in a variety of diseases. Perfusion measures have been a cornerstone of nuclear medicine (SPECT and PET) studies for characterizing brain regions affected in neurological disease. 

Pears MR, Cooper JD, Mitchison HM, et al. High resolution 1H NMR-based metabo-lomics indicates a neurotransmitter cycling deficit in cerebral tissue from a mouse model of Batten disease. J Biol Chem. 2005 280 42508-42514. 

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